1. Field of the Invention
The present invention is related to a machine tool of the type having a rotatably mounted spindle shaft having a longitudinal axis of rotation and adapted for having coupled thereto a tool holder having a plurality of cutting inserts which are adjustable radially of the axis before, during, or after the cutting operation depending on the work being done.
2. Description of the Prior Art
Presently, parts can be machined to very close tolerances and at high speeds often without the need for secondary operations such as honing, grinding and lapping.
Great improvements have been made in machine tools, particularly those tools which provide automatic adjustment for cutting tool inserts radially inward or outward, as and when desired, to, for example, compensate for wear of the cutting edge, for boring, turning, grooving, finishing on a retract stroke, to withdraw the tool from a workpiece without marking the side wall of a finished bore, or for bore sizing and contour boring. One cutting machine which has provided significant advances in achieving these results is described in U.S. Pat. No. 3,740,161 and is made by GTE Valeron Corporation. With this tool, the cutting edges of all of the inserts can be automatically adjusted outwardly and inwardly precisely and quickly without human intervention and possible error, and downtime. However, the hydraulic mechanism used has caused alignment concerns which have limited the use of such equipment to its fullest advantage. Alignment concerns have been particularly difficult at high speeds.
Another problem results from the fact that often state of the art cutting machines do not include hydraulic systems. With such machinery it is necessary to modify the basic cutting machine by supplementing it with an auxiliary hydraulic system. In addition to the fact that such an addition must be provided for, problems associated with the use of hydraulic apparatus are incurred. For example, hydraulic systems include various hydraulic pumps which tend to be noisy and also require attention in order to be maintained in acceptable operating conition. In addition, other hardware associated with a hydraulic system is required which adds to the cost and upkeep of such apparatus. In addition, it is not uncommon for hydraulic systems to operate continuously throughout the day even though the particular machine with which the system is associated may not be in use. Such continuous use obviously involves an unnecessary use of energy. In addition, various components of a hydraulic cutting machine may have a reduced life due to repetitive operation caused by continual stroking of the hydraulic mechanism.
The addition of a hydraulic system also will require the addition of a control system to control the hydraulic equipment. Thus two systems will be required; one to control the cutting tool per se and one to control the hydraulic apparatus.
A further concern is that the actual control of the orientation or location of the cutting tool tends to be rather complicated when a hydraulic system is being used.
A related problem is that the known prior art machine tools are not as compact as desired in the sense that the entire mechanism which causes radial movement of the inserts is not mounted directly to the spindle shaft of the tool, and this tends to aggravate the alignment concern.
It is highly desirable to provide a machine tool which can be operated without concern about tool alignment considerations. It is also desirable to solve this problem and at the same time eliminate the need for an auxiliary system, particularly an auxiliary hydraulic system with all of the problems noted herein associated with such a system. It is also desirable to provide a machine tool wherein what is referred to in the art as a closed loop system may be utilized. In such a system, means are provided for orienting or locating the cutting tool in such a manner that simultaneously with such tool orientation signals are sent back to the orientation means to identify the cutting tool location and thereby facilitate proper positioning of the tool.